This invention relates to improvements in tamper evident closures and the method of manufacture of the same.
We are aware that others have previously provided tamper evident closures including a cap and a security ring and in which the cap breaks away from the security ring on removal of the cap from the container, the security ring remaining on the container and evidencing that the container has been opened. In all such devices of which we are aware, for instance, as shown in U.S. Pat. Nos. 3,329,295; 4,196,818; 4,322,009; 4,401,227; and 4,506,795, the cap and security device are molded as an integral one piece unit. In view of the criticality of certain dimensions of tamper evident closures of this type, particularly in the formation of the frangible links by way of which the cap is molded to the security ring, their manufacture calls for the use of complex molds, an involved cutting operation, or both.
The cap and security ring of earlier tamper evident closures are molded in one piece, the entirety of which is of the same material and of the same color. Also, in devices of this type, the side walls thereof have a plurality of openings extending therethrough, to the sides of which are provided the links which connect the cap to the security ring. Thus, these devices are particularly vulnerable to side shear and separation of the cap from the security ring during the hoppering and sorting phases of the capping operation.
It is a primary object of this invention to provide a tamper evident closure in which the cap is formed independently and separately from the security ring thereof, the cap and security ring thereafter being interconnected by a plurality of spaced apart fused bridges which comprise frangible zones of weakness adapted to rupture during removal of the cap from the container.
A further object is the provision of a tamper evident closure in which the cap thereof may be formed of a material different from that of the security ring thereof. Thus, for instance, the cap can be formed of relatively rigid material, in order to withstand higher application torques and to preclude overstripping on the bottle finish, and the security ring can be formed of more flexible material to facilitate the application thereof over the security ring retaining shoulder of the container neck during attachment of the closure to the container neck.
Another object of the invention is the provision of a tamper evident closure in which the cap may be molded of a different color from the security ring. This will enable use of color coding for such as designating the contents of variously color-coded containers as being of different strengths, mixtures, etc. The use of two different colors provides a much wider selection than would be possible if only one color were available, i.e., the cap and security ring being of the same color. Also, molding in a color provides a permanent color coding that will not rub off or otherwise be removed from the cap and security ring.
A still further object of this invention is the provision of a method of manufacture of a tamper evident closure in which the cap is molded separately and independently from the security ring thereof and for the assemblage and interconnection together of cap and security ring to provide a unitary tamper evident closure.
A continuing problem has been to provide a tamper evident closure in which the links between the cap and security ring thereof are such as to enable the cap to break cleanly away from the security ring on removal of the cap from the container neck and yet are sufficiently strong to prevent separation of the cap from its security ring during the hoppering, sorting and attaching phases of the capping operation. Due to the inherent problems of flow and distribution, it has proven difficult to mold an area of appropriate frangibility into the links that extend between a cap and its security ring and, since it is rare that mass production techniques will produce a perfectly cylindrical closure, weakening of the links by cutting away a portion thereof is imperfect, at best, some cuts being too deep, while others are not deep enough.
It is thus a still further object of this invention to provide a method of manufacture of tamper evident closures in which the areas of frangibility of the interconnections between the cap and security ring thereof are formed as a feature of interconnection and can thus be carefully crafted to provide appropriate zones of weakness which are of sufficient strength to withstand the hoppering, sorting and attaching operations, but will break cleanly on removal of the cap from a container neck.